1. Field of the Invention
The present invention relates to a disk drive, and particularly, to a turntable apparatus, on which a disk is mounted so that the disk can be rotated, for a disk drive.
2. Description of the Background Art
FIG. 1 is a plan view showing a pick-up base of a disk drive according to the conventional art.
As shown therein, an optical pick-up 3 is installed on a pick-up base 1 so as to be rotatable. The pick-up base 1 is installed so that a front end part of the pick-up base 1 can be elevated as a predetermined angle centering around a rear end part on a main base (not shown).
The optical pick-up 3 radiates light on a signal recording surface of the disk and detects reflected light, and functions as recording a signal on the signal recording surface of the disk or reproducing the recorded signal. The optical pickup 3 performs linear reciprocating movements as guided by pick-up guide shafts 4 and 4′ on the pick-up base 1.
On the other hand, a driving force for moving the optical pick-up 3 is provided by a sled motor (not shown) generally, and the driving force of the sled motor is transmitted to the optical pick-up via a lead screw (not shown).
On the other hand, a spindle motor 7 for providing a driving force to rotate the disk is installed on a front end of the pick-up base 1. In addition, a circuit board 8, on which a structure for controlling the operation is disposed, is mounted on a lower part of the spindle motor 7.
In addition, a plurality of fixing shafts 9 are caulked on the pick-up base 1. Herein, a spring (not shown) is inserted on an outer surface of the fixing shaft 9, and the spring is installed between a bottom surface of the pick-up base 1 and an upper surface of the circuit board 8 to provide the circuit board 8 with an elastic force toward the direction far from the pick-up base 1.
Also, a skew screw (not shown) is installed on the fixing shaft 9 as penetrating the circuit board 8, and the skew screw fixes the circuit board 8 on the pick-up base 1, and at the same time, controls a distance between the upper surface of the circuit board 8 and the bottom surface of the pick-up base 1. Actually, the skew screw controls the height of the spindle motor 7 to make the light radiated from the optical pick-up 3 incident and collected vertically to the signal recording surface of the disk. On the other hand, the controlling operation of the skew screw is called as skew controlling.
Especially, a turntable 10 on which the disk is mounted is installed on an upper end of the spindle motor 7. The turntable 10 rotates the disk as rotated by the spindle motor in the state that the disk is mounted on the turntable.
FIG. 2 is showing a detailed structure of the turntable 10. The turntable 10 is press-fitted into a rotational shaft 7′ of the spindle motor 7. In addition, a friction member 12 is installed on a boundary of an upper outer circumferential surface on the turntable 10 to prevent the disk which is mounted on the turntable 10 from being rotated relatively when the turntable 10 rotates.
In addition, a guide cap 14 is installed on an upper part of the turntable 10. The guide cap 14 is installed on the rotational shaft 7′, and a spring 15 is installed between the turntable 10 and the guide cap 15. The spring provides the guide cap 14 with the elastic force so that a central hole of the disk can be mounted on the guide cap 14 exactly.
Therefore, a slant portion 14a for guiding the central hole of the disk is disposed on boundary of outer circumferential surface of the guide cap 14. A stopper 16 is installed on an upper end of the guide cap 14 to prevent the guide cap 14 from being drifted away from the rotational shaft 7′.
However, there are some problems in above conventional art as follows.
The turntable 10 is installed as being press-fitted into the rotational shaft 7′. Therefore, the rotational shaft 7′ and the turntable 10 rotate integrally with each other without a relative motion. However, if the surface of the turntable 10 does not make a right angle for the rotational shaft 7′, the turntable 10 is greatly shaken when the turntable 10 is rotated.
As described above, when the turntable 10 is trembled excessively, the disk is also trembled, and therefore, the operations of recording or reproducing the signal on the disk via the optical pick-up. Accordingly, the reliability of the disk drive is greatly lowered.